In the past two decades increased interest has been devoted to developing ‘compliant’ robotic systems. Compliance in robotics implies ‘give’ or ‘softness’ in what is typically a rigid, linked system. In early applications to industrial robots, compliant systems have allowed robots to perform force sensitive tasks (e.g. surface grinding) while remaining stable during their operation. More recently, interest in developing ‘wearable’ robots or exoskeleton systems have been demonstrated. The typical role of ‘wearable’ robotic system is to enhance a person's strength. Compliance in this type of application is imperative to ensure safety for the operator, as the robotic system is not tucked safely away behind a cage, as in a factor floor robot.
The process of interfacing robotics directly onto humans introduces design issues of weight, power consumption and again safety. To meet the challenges laid by these constraints, actuators based upon spring concepts offer a promising solution. Unlike traditional motor approaches, spring based actuators are inherently compliant, energy conservative and lightweight. Through manipulation of an actuator's ‘effective’ structure, variations in actuator stiffness can be obtained. A ‘Force Suit’ constructed from these actuators can be created, thus enabling the disabled or weak to regain lost functionality and independence in their everyday lives.